TUCSON, Ariz. — The human Y chromosome is one of the most studied pieces of genetic material in the history of science. Few things are as well understood. That’s why it caught scientists so off guard when an African American man’s Y chromosome turned out to be something they had never seen before.

Not only is the peculiar variation of South Carolinian Albert Perry’s Y Chromosome rare, it has pushed back the age for the father of all men — the genetic Adam, if you will — by over 100,000 years.

“Our analysis indicates this lineage diverged from previously known Y chromosomes about 338,000 ago, a time when anatomically modern humans had not yet evolved,” said University of Arizona scientist Michael Hammer, lead author on a new study detailing the latest findings on the matter. “This pushes back the time the last common Y chromosome ancestor lived by almost 70 percent.”

Perry’s DNA was submitted to the National Geographic Genographical Project, which seeks to study ancient human migrations through DNA markers. Analysis could not recognize Perry’s Y chromosome as belonging to any known group.

Technicians at Family Tree DNA, which processes the samples for the project, compared the chromosome to some 6,000 known Y chromosomes. Eventually, they found 11 similar ones, all from a particular small village in Camaroon. That could mean the most recent common ancestor of all human males came from that region, or that later descendants migrated there.